Nylon cord package and method of preparing the same



Dec; 13, 1960 E. T- LESSIG ET AL Filed June 28, 1954 Jr? 2 m 2/ iii}:-

INVENTORS ED WARD TLEssiG BY MA T THEW W VWLso/v ATTY.

United State NYLON CORD PACKAGE AND METHOD OF PREPARING THE SAME Edward T. Lessig, Cuyahoga Falls, and Matthew W. Wilson, Stow, Ohio, assignors to The B. F. Goodrich I Company, New York, N .Y., a corporation of New York Filed June 28, 1954, Ser. No. 439,532 17 Claims. (Cl. 242-173) This invention relates to improved cord formed of nylon or like fibers and to the method of preparing the same whereby cord having desired physical properties is prepared in a manner facilitating handling thereof in manufacturing cord-reinforced articles formed of rubber or other elastomers.

Vehicle tires, belts, and many other rubber articles are customarily reinforced by cords, the cords being frequently incorporated into the rubber or other elastomer in weftless form. This is achieved by disposing the cords in parallel relationship and then binding them together by a layer or coating of the rubber or other elastomer after which additional rubber or other elastomer after which additional rubber or other elastomer may be adhered thereto. Such reinforcing cords are general'y formed of a plurality of fibers twisted together to form yarns or strands with several yarns o-r strands plied by twisting them together to comprise the cord. In order to secure a balanced cord, i.e., one which does not twist upon itself when allowed to hang in a free loop, the ratio of the number of turns per inch imparted to the strands or yarns for cords of a given size and number of filaments, relative to the number of turns per inch imparted to the fibers forming the strands or yarns falls within a narrow range and any very material departure from this range results in unbalance.

The range of ratios of turns which results in a balanced cord does not, however, necessarily produce a cord having the optimum physical properties for reinforcing articles in which the cords are incorporated. For example, it has been found that by lowering the twist of the fibers or filamentscomprising a yarn or strand of a .cord and increasing the twist of the several yarns or strands forming the cord, the latter has greater fatigue resistance with no increase in stretch, characteristics which are highly desirable in cords used to reinforce vehicle tires. This change in the twist ratio, however, results in unbalance of the cord which is especially pronounced when the cord is formed of nylon filaments.

Unbalance in cord is particularly objectionable when the cord is supplied from a creel, i.e., a frame upon whicha plurality of cones, tubes or like packages of the cord are supported and from which the cord passes through eyelets or other guides to the place of utilization. In Such a structure, any variation in tension on a cord provides an opportunity for the latter to kink or knot with resulting breaks of the cord or irregularities in the article in which the cord is incorporated. Nylon cord is especially difficult to handle because, even when balanced, such cord has a tendency to be wild in the creel. That is, the relatively low coefiicient of friction between adjacent convolutions of the cord results in a tendency for it to pull off the cones or tubes too rapidly upon a momentary increase in tension or to slough off the cones or tubes upon a decrease in tension. This characteristic coupled with an unbalanced twist ratio has resulted in it being extremely diflicult, if not impossible, to handle unbalanced nylon cord in a creel. Consequently, it has 2,964,262 Patented Dec. 13, 1960 not been possible to employ nylon cord which is twisted in a manner to provide optimum characteristics for reinforcement in vehicle tires.

An object of this invention is, therefore, to provide irnproved cord and method of preparing the same whereby the twists imparted to the filaments and/ or the yarns or strands can be varied from that normally productive of a balanced cord without objectionable unbalance and/or wildness of the cord when used in a creel.

Another object of the invention is to provide improved nylon cord and a process of preparing the same wherein the yarns or strands of filaments comprising the cord are moistened with a wetting agent prior to twisting of the yarns or strands in forming the cord, which agent also dries to form a deposit on the cord that increases the cord-to-cord friction, whereby twisting strains in the cord are reduced and wildness of the cord in a creel is substantially eliminated.

A further object of the invention is to provide an improved cord and method of preparing the same, as defined above, wherein the wetting agent is an aqueous solution of an organic salt of rosin amine.

An additional object of the invention is to provide an improved cord and method of preparing the same, as defined heretofore, in which the wetting agent is an aqueous emulsion of a sulfonated petroleum oil.

A more specific object of the invention is to provide an improved nylon cord and method of preparing the same wherein a plurality of twisted yarns or strands of filaments are moistened by a wetting agent after which the moist strands are twisted together to form a cord that is wound upon a cone or tube for use in a creel, the ratio of the number of turns of the strands to the number of turns of the bundle of filaments comprising the strands being such that the cord has optimum tensile, flexure and elongation characteristics without regard to the twist ratio normally required for balance with the said moistening before twisting and subsequent drying of the cord reducing any strains developed by the twisting and increasing the cord-to-cord friction so that wildness or kinking of the cord in the creel is prevented.

The invention further resides in certain novel steps of procedure and features of the improved cord produced thereby, and further objects and advantages of the invention will be apparent to those skilled in the art to which it pertains from the following description of the presently preferred embodiment thereof described with reference to the accompanying drawing forming a part of this application and in which: I

Fig. l is a fragmentary, somewhat schematic, elevational view of a portion of a creel illustrating the slacking or sloughing off of conventional nylon cord from a cone thereof;

Fig. 2 is an enlarged view of a freely hanging loop of cord exhibiting no characteristics of unbalance;

Fig. 3 is an enlarged view of a loop of unbalanced cord showing the kinking thereof; and

Fig. 4 is a somewhat diagrammatic, fragmentary perspective view of means which may be employed to moisten and twist strands of nylon fibers to produce cord in accordance with this invention.

The formation of a weftless reinforcing fabric for use in vehicle tires or the like requires that a very large number of cords be simultaneously supplied from separate cones, tubes or spools thereof and directed into closely adjacent parallel relationship. This can be most advantageously efiected by the use of a creel which, as is schematically represented in Fig. 1, comprises a framework 10 having spaced spindles or pins 10a on which the cord cones, tubes or spools 11 are supported. In the illustrated creel, the cord cones 11 are supported with their axes inclined at a convenient angle relative to the vertical members of the framelo of the creel. Hence, the cords are pulled from the cones over the outer or free ends of the latter and are directed into the desired path through eyelets or guides 12 supported upon the frame after passing through tension' devices TD.

These devices as here shown comprise a pair ofsuperposed disks supported upon a vertically extending pin with the cord passing betweenthe disks and subjected to the tension exerted by the weight of the latter.

The cords issuing from the creel are pulled through apparatus, not shown, wherein they'are subjected to a controlled tension and are then provided with a coating of rubberor other elastomer. Under ideal conditions all the cords within the creel'would be under substantially equal, constant tension. However, this condition is seldom if ever achieved with the result that one or more of the cords such as 13 may momentarily be somewhat slack and/or one or more convolutions of such a cord will loosen on the cone so that the cords hang therefrom in a loop or loops 14. This tendency of cord to slack or slough off a cone is known as wildness" and is due, at least in part, to insufficient friction between contacting convolutions of the cords, the tendency to wildness being especially pronounced with nylon and other synthetic linear condensation polymer cords which have a low coefficient of friction. Due to the very large number of cones employed in a creel, excessive slackness or sloughing off from the cones will result in tangling and/or kinking of the cords as the result of interference between the cords. Moreover, when the cord employed is unbalanced, the dlfficulties are accentuated since wildness is increased and slackness in a cord does not generally result in a free hanging loop 14 but rather each loop of appreciable size tends to twist or'kink upon itself as indlcated at Ma. Hence, there not only is increased potential tangling between the cords because of the increased wildness but, in addition, each cord is itself capable of forming knots or twists.

It is, of course, well known in the textile art that a balanced cord can be produced by keeping the number and direction of twists im arted to the fibers and yarns in forming a cord within a certain range of values. Thus, for a cord employing bundles of filaments of 840 denier twisted to form yarns and two yarns twisted to form a cord, balance isachieved when the bundles of filaments are twisted fourteen turns to the inch to form the yarns and the yarns twisted in the reversed direction ten turns to the inch. When such a cord is allowed to form a loop it hangs freely as indicated at 15 in Fig. 2 and does not tend to kink or twist. Unfortunately, however, a cord of this twist ratio does not have optimum characteristics for use as a reinforcing member in articles such as vehicle tires or the like. A cord which has a much betterfatigue resistance is one formed from filaments of the same denier having the same number of yarns but with the filament bundles comprising the yarns twisted twelve turns to the inch and the yarns twisted together eleven turns to the inch. Unfortunately, however, such a cord is unbalanced and. tends to twist or kink upon itself when allowed toform a loop, as indicated at 15a in Fig. 3, with consequent difficulties in handling. In-order to approximate like fatigue resistance in a balanced cord formed in the conventional manner it would be necessary to change the twist imparted to the filaments to fifteen turns to the inch while keeping the twists imparted in plying the yarns to eleven turns to the inch. Although this results in a properly balanced cord it also increases the ability of the cord to elongate under tension which is undesirable in a vehicle tire.

Similar difiiculties are encountered when the twist ratios are changed to improve other characteristics ofthe cord. That is to say, altering, the twist ratio to secure greater strength, better fiexure, less elongation, and the like, results inunbalance ofthe cord rendering it difiicult, if not impossible, to utilize it in a creel. This lack of balance is particularly troublesome with cords formed from nylon fibers because, as mentioned above, the low coefiicient of friction of the surface of the cords tends to accentuate the condition of slacking or sloughing off of the cords from the cones used in a creel and this, in turn facilitates formation of twists, kinks and knots. Consequently, it has been necessary to effect a compromise with respect to desired characteristics in nylon cords so that they may be handled without undue attention from the oprator and/or imperfections in the product.

In accordance with this invention, it is now possible to employ, in a creel, cords having twist ratios which would normally result in an unbalanced condition without, however, also having the attendant difficulties normally prescut when unbalanced cords are utilized. Therefore, by utilizing this invention, it is now possible to select the twist ratio for the cords which will provide the optimum physical characteristics of the cords as reinforcing members in vehicle tires, or the like, without undue regard for whether or not the resulting twist ratio will produce unbalance of the cord. These advantages result from the fact that cord formed in accordance with this invention has the strains resulting from twisting partially relieved and, in addition, the surface of the cord receives a deposit which increases the coefiicient of friction or the tackiness thereof. Hence, the cord convolutions have less tendency to slack or slough off a cone, tube or spool, and any slackness which may occur in using such cord in a creel does not result in excessive kinking or twisting. These advantages are especially pronounced when the inventIon is applied to cord formed of nylon filaments or fibers although the invention is not limited thereto.

As previously stated, the essence of this invention resides in moistening the yarns of the textile fibers with a wetting agent before the yarns are twisted together to form a cord, the moistening agent being such that it wets the yarns sufiiciently to substantially relieve the strains produced therein by the twisting operation so that the cord no longer has the tendency to relieve the twisting strains through kinking or twisting after the'cord has dried. In addition, the moistening or wetting agent should be such that when dried, it forms a deposit on the surface of the cord providing a slightly tacky" surface, or one which has a sufficient stiffening or sizing action on the cord surface so that the convolutionsof cord tend to remain in place upon a cone or tubeuntil purposely pulled therefrom. The moistening agent will, of course, be selected in accordance with the composition of the fibers comprising the cord and is such that the stiffening or sizing action does not persist to an appreciable extent after the cord is drawn through several guides or eyelets to change the path of the cord and deliver it to the dip tank. When the cord is nylon, the moistening agent may, for example, be an aqueous solution of an organic salt of rosin amine, an aqueous emulsion of a sulfonated petroleum oil, or materials of like characteristics.

As an example of the manner in which the invention may be practiced, bundles of nylon filaments were twisted together approximately twelve turns to the inch to provide separate yarns such as 16 and 17. These-yarns were then moistened before twisting'them together by passing the yarns through suitable guides 18-into' contact with the surface of a roller 19 that had a portion of its periphery immersed in a quantity of a wettingagent 20 for the fibers after which the yarns passed overand between squeeze rolls 21, 22 and 23 that removedexcess moisture. Two of the yarns, such as 16 and' 17, were then brought together and twisted to form a cord by a conventional mechanism, schematically represented at 24 in Fig. 4 of the drawing, afterwhich the'resulting cord passed through a suitable guide or guidesZSto aring traveler 26 which wound the cord into a suitable package, such as a cone 11.

The number of turns imparted to the yarns in forming the cord was eleven to the inch which would normally be productive of an unbalanced cord. Thus, experiments with a cord of this twist ratio but formed in a conventional manner without moistening prior to twisting demonstrated that the cord of such twist ratio was too wild .for satisfactory creel performance and exhibited excessive twisting. However, formation of the cord in the manner just described, by moistening the yarns with a wetting agenttherefor and twisting the same together while still moist, resulted in a cord having satisfactory characteristics for use in a creel with no excessive wildness or tendency to twist.

The liquid employed to moisten the yarns was principally water with a substance incorporated therein which increases the wetting action of the water upon the nylon fibers. The proportion of such substance or additive should be in the order of 0.1% to 3.0% by weight and among satisfactory substances are: organic salts of rosin amine, such as rosin amine acetate; an emulsion of sulfonated petroleum oil, such as that commonly sold by oil products companies, and other materials of like characteristics.

Cords'formed in accordance with this invention not only exhibit reduced wildness in the creel but also achieve this desired result without appreciable loss in tensile strength. Thus, a nylon cord of the above defined denier and twist ratio which was dry-twisted was found, on test, to have a tensile strength of 28 pounds and an unbalanced condition of sixteen twists to the yard. When a cord of like size and twist ratio was prepared in accordance with this invention, by twisting the yarns after moistening them with an aqueous solution containing 0.75% of rosin amine acetate prior to the twisting, the tensile strength was 27.6 pounds and the unbalanced condition was only 6.9 twists to'the yard, an amount which proved satisfactory for use in a creel. Likewise, a cord'of like size and twist ratio which had the yarns moistened with an aqueous emulsion of sulfonated petroleum oil, with the oil constituting 0.75% part by weight, exhibited a tensile strength of 27.8 pounds and an unbalanced condition of only 7.3 twists per yard. These cords were both definite improvements over the result achieved when a cord was formed from yarns which were moistened only with water prior to the twisting. Thus, a cord so treated exhibited a tensile of 27.6 pounds but had an unbalanced condition of 13.7 twists per yard. Improved results corresponding to those achieved when using 0.75% of the wetting agent were also obained when other percentages of wetting agent were employed in the liquid used to moisten the yarns prior to twisting, these other percentages being within the range mentioned above.

In addition to the reduced unbalance condition of cords formed in accordance with this invention, the satisfactory performance of the cords in the creel is also due to the fact that, after the cords have been dried, the material employed in the moistening forms a deposit thereon which impartstackiness or stiffness similar to that which is imparted by sizing. This increases the ooefiicient of friction between adjacent convolutions of the cord on the cones or tubes so that the said convolutions do not tend to slide or slough off. Consequently, when such cords are employed in a creel, variations in tension applied to the cords does not result in the formation of loose convolutions or loops similar to those indicated 14 in Fig. 1. This coupled with the fact that there is less tendency for the cords to twist upon themselves reduces the kinking and twisting so that the twist ratio of the cords need no longer be restricted to the narrow range of values heretofore necessary. The reduction in the unbalance of the cord resulting from formation thereof in accordance with this invention may be due in part to the stiffening action of the moistening material drying upon the cords. However, it is believed that the improvement is also due to the fact that the moistening of the filaments by a wetting agent sufiiciently softens the filaments or fibers so that the strains imparted by twisting are not as pronounced or are partially relieved and hence there is less tendency for the filaments to return to an untwisted condition. Hence, there is correspondingly less tendency for kinking or twisting of the cord.

In practicing this invention as herein illustrated and described, the cords are wound upon the cones or tubes as the cords issue from the twisting apparatus. It will be understood, however, that the moisture content of the twisted cords can be adjusted to optimum value either before or after winding upon the cone.

Although the preferred embodiment of the invention relates to its use in preparing nylon cords, and the specific examples given relate to such preparation, it will be understood that the invention may be employed for cords of other synthetic linear condensation polymers and with other wetting agents. Moreover, the invention is not restricted to the formation of nylon cords having the specific number of turns mentioned by way of example but may be employed to advantage in forming cords having other twist ratios. Furthermore, the invention may be advantageously employed to reduce wildness of nylon cord even when the latter has a twist ratio that would normally be productive of a balanced cord, the improvement in this instance being due to the stitfness or tackiness imparted to the yarns during the processing so that the latter have less tendency to slack or slough off cones during delivery of the cords therefrom. In view. of these and other adaptations, of the invention, which will be apparent to those skilled in the art, it is evident that the invention is not limited to the specific details or examples herein set forth except as may be required by the spirit and scope of the appended claims.

Having thus described the invention, we claim:

1, The process of preventing wildness of cords when used in a creel comprising moistening yarn formed from a plurality of filaments of a synthetic linear condensation polymer with a wetting agent having a temporary sizing action on the yarn when dried thereon, twisting a plurality of moistened yarns together to form a cord, and winding the cord into a package thereof suitable for use in a creel with a portion of the wetting agent dried on the cord, whereby a part of twisting strains are relieved and the friction between adjacent convolutions of the cord is increased to the extent that sloughing of the cord from the package is prevented.

2. The process of preparing nylon cord for use in a creel comprising moistening nylon yarn with a liquid composition which wets nylon fiber and also forms a deposit increasing the coefficient of friction of the surfaces of the fibers when dried thereon, twisting a plurality of the moistened yarns together while moist to form a cord, and winding the cord upon cones or tubes suitable for use in a creel.

3. The process of preparing nylon cord for use in a creel comprising moistening nylon yarn with water containing an organic salt of rosin amine, twisting a plurality of the moistened yarns together while moist to form a cord, Winding the cord upon cones or tubes suitable for use in a creel without rinsing so that a light deposit of said salt is formed on the cord by evaporation of the water from the moistened yarns.

4. The process as defined in claim 3 wherein the said organic salt is present in a concentration of from 0.1 to 3.0% of the weight of the liquid.

5. The process of preparing nylon cord for use in a creel comprising moistening nylon yarn with water containing rosin amine acetate, twisting a plurality of the moistened yarns together while moist to form a cord, and

winding'the moistened cord upon cones or tubes suitable for use in a creel whereby at least a part of the strains-imparted by twisting are relieved and a friction increasing deposit is formed on the cord surfaces.

6. The'process of preparing nylon cord for use in a creel comprising moistening nylon yarn with an aqueous emulsion of a sulfonated petroleum oil, twisting a plu' rality of'the moistened yarns together while moist to form a cord, and winding the moistened cord upon cones or tubes suitable for use in a creel whereby at least a part of the strains'imparted by twisting are relieved and a friction increasing deposit is formed on the cord surfaces.

7. The process as defined in claim 6 wherein the said cient to normally produce an unbalanced cord, and wind-' ing the cord upon cones or tubes suitable foruse in a creel.

9. The process of preparing nylon cord for use in a creel employed to form a weftless fabric comprising providing a plurality of nylon yarns each including a bundle of nylon fibers twisted a plurality of turns per inch, moistening the nylon yarns with a liquid composition which wets thenylon fibers and also forms a deposit increasing the coefiicient of friction of the surfaces thereof when dried thereon, twisting a plurality of the moistened yarns together while moist to form a cord having a plurality of turns per inch sufficient to normally produce an unbalanced cord, and winding the cord upon cones or tubes suitable for use in a creel.

10. A wound package of cord suitable for use in a creel, the said package containing a plurality of superposed cord convolutions with the said cord comprising a plurality of twisted yarns each formed of a plurality of filaments of a synthetic linear condensation polymer twisted together while moistened with a wetting agentand provided with a deposit from the wetting agent of a substance which increases'the coeflicient of friction of the 8-, cord. whereby the ,cord convolutions are retarded from sloughing otfthe package during withdrawal of the cord therefrom.

11. A=wound package of cord as defined in claim 10 wherein thedeposit comprises an organic salt of rosin amine.

12; A wound package of cord as defined in claim 10 wherein the deposit comprises rosin amine acetate.

13'. A wound package of cord as defined in claim 10 wherein the-deposit comprises the solids from an aqueous emulsion of a sulfonated petroleum oil.

14. A wound packageof cord suitable for use in a creel, the said package containing. a plurality of superposed cord convolutions with the said cord comprising a plurality of twisted yarns each formed of a plurality of nylon filaments twisted together, the twist ratio. of the filaments and iyarns being within the range which normally produces anunbalanced cord'with the said cord exhibiting less than the normal amount of unbalance, and a deposit of a substance onthe yarns which increases the coefficient of friction of the cord, whereby the cord convolutions are retarded from sloughing otf'the package during withdrawal of the cord therefrom.

15. Atwound package of'cord as defined in claim 14 whereinthe' deposit comprises an organic salt of rosin amine.

16. .A wound package of cord as defined in claim 14 whereinthe deposit'comprises rosin amine acetate; 7

17. A wound package of cord as defined in claim 14 wherein the deposit comprises the solids from an aqueous emulsion of a sulfonated petroleum oil.

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